Sharing a consultant would seem to be an embodiment of coordination between a candidate and an independent group, something prohibited under federal law. But TargetPoint is just one of a handful of interconnected firms in the same office suite in Alexandria, Va., working for either the Romney campaign or the super PAC Restore Our Future.

Elsewhere in the same suite is WWP Strategies, whose co-founder is married to TargetPoint’s chief executive and works for the Romney campaign. Across the conference room is the Black Rock Group, whose co-founder — a top Romney campaign official in 2008 — now helps run both Restore Our Future and American Crossroads, another independent group that spoke up in defense of Mr. Romney’s candidacy in January. Finally, there is Crossroads Media, a media placement firm that works for American Crossroads and other Republican groups.

The overlapping roles and relationships of the consultants in Suite 555 at 66 Canal Center Plaza offer a case study in the fluidity and ineffectual enforcement of rules intended to prevent candidates from coordinating their activities with outside groups. And there has been a rising debate over the ascendancy of super PACs, which operate free of the contribution limits imposed on the candidates but are supposed to remain independent of them.

While insisting that the tangle of connections does not violate any laws, Alexander Gage, TargetPoint’s founder, said he understood how it could look “ridiculous.” His own firm had taken steps, he said, to prevent improprieties, including erecting “a fire wall” separating employees who work for the Romney campaign and the super PAC.

“We go to great lengths to make sure that we meet all legal requirements,” he said. “I have removed myself personally from working on either Restore Our Future or Romney stuff because of this sort of potential conflict of interest.”

The prohibition against candidates working in concert with independent political committees has its roots in Watergate-era reforms intended to prevent large donors from gaining improper influence over elected officials. But it has taken on added significance in the wake of recent court decisions that opened the spigot for unlimited contributions to the independent groups.

Super PACs have collected more than $100 million so far, much of it from a relatively small collection of well-heeled individuals or companies who are free to give millions to these outside groups but no more than a few thousand dollars to a candidate’s own committees. Those unlimited contributions are fueling a barrage of negative advertising in the Republican primaries.

But while the Federal Election Commission has established elaborate, though narrow, guidelines for determining whether the creation of a specific campaign advertisement violates the coordination ban, it has not focused on other kinds of activities between all PACs and candidates. Rules the commission adopted in 2003, still on the books, allow for regulation of this gray area, but they have been largely ignored.

“Most of the focus so far has been on the ads, but there may be a lot of other activity that is being coordinated between the campaigns and the super PACs that could be seen as resulting in a benefit to the campaign,” said Lawrence M. Noble, a campaign-finance lawyer at Skadden, Arps and a former general counsel for the election commission.

The regulations on coordination include a general prohibition on expenditures “made in cooperation, consultation or concert with, or at the request or suggestion” of candidates and their representatives. The commission’s records show that when devising this rule, it turned aside pleas from political groups to limit enforcement only to ads, saying such a narrow focus was not what Congress intended.

Nine years later, however, there is little evidence that the commission has followed through on this intent.

The commission, made up of three Republicans and three Democrats, has long been divided along partisan lines on how far to go in enforcing rules on coordinated expenditures, often resulting in paralysis.

Last fall, the commission was asked by American Crossroads if it could broadcast certain ads, “fully coordinated” with a candidate, who would be consulted about the script and appear in the advertisement. The group argued that it would not be improper as long as the ad ran outside of a time window established by the commission for “electioneering communications.”

The commission deadlocked and could reach no conclusion.

“The campaigns know the F.E.C. isn’t going to enforce the law, and so they’ve decided to do whatever they want,” said Fred Wertheimer, whose watchdog group, Democracy 21, has complained to the Justice Department about the lack of enforcement. “What is going on is just absurd.”

The commission declined to comment for this article.

From the start, there has been no doubt that the super PACs are closely entwined with the candidates they support.

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Priorities USA Action, which supports President Obama, was formed by two former White House aides, and Obama administration officials are helping it raise money. A former top aide to Newt Gingrich helps run a pro-Gingrich super PAC, Winning Our Future. And Foster S. Friess, a major donor to Rick Santorum’s super PAC, often travels with the candidate.

Mr. Romney has often blurred the distinction between his campaign and Restore Our Future. Last summer, discussing a large donation to the super PAC by one of his former business partners, Mr. Romney characterized it as a donation to himself. He appeared at a fund-raiser for Restore Our Future and has publicly encouraged people to donate to it.

Campaign spending reports filed by both the super PAC and the Romney campaign shed additional light on just how closely interconnected the two entities are.

Restore Our Future, for example, has paid TargetPoint Consulting nearly $350,000 for survey research. Meanwhile, the Romney campaign has paid TargetPoint nearly $200,000 for direct mail consulting. In one instance, the campaign and the super PAC paid TargetPoint on the same day.

Mr. Gage, a senior strategist in Mr. Romney’s 2008 campaign, is married to Katie Packer Gage, a deputy campaign manager of the current Romney campaign. The campaign has paid her firm, WWP Strategies, nearly $250,000 for strategy consulting.

Both of their companies share an office suite with the Black Rock Group, a political consulting firm co-founded by Carl Forti, who worked as political director for Mr. Romney’s 2008 campaign and helps direct Restore Our Future. The super PAC has paid Black Rock about $21,000 for communications consulting.

Mr. Forti declined to comment. Mr. Gage said that his firm had a separate work space from Black Rock, divided by a conference room. “It’s not like we’re a commingled office,” he said.

His wife’s office for WWP Strategies is in the same area as TargetPoint’s, he said, but she has been working out of the Romney headquarters in Boston for the most part. Mr. Gage said they do not discuss the campaign.

Gail Gitcho, a spokeswoman for the Romney campaign, said the campaign followed both the letter and the spirit of the law on coordination.

“We know the law,” she said, “and we abide by it scrupulously.”

The spending reports suggest that the Romney campaign and the super PAC, if not coordinating, have been closely following each other’s fund-raising events, though Ms. Gitcho emphasized that no joint fund-raisers had been held.

Last summer, the super PAC and the Romney campaign employed Creative Edge Parties, a New York catering company, and each sent it a payment on the same day: the super PAC gave a check for $1,676 for a “fund-raising event,” while the Romney campaign sent $1,584 for “facility rental/catering services.”

On another occasion, Restore Our Future paid $1,500 as a fund-raising expense to the Waldorf Astoria in New York, where the Romney campaign held a fund-raiser in December. Around the same time, the Romney campaign paid the Waldorf $19,000 for “facility rental/catering services” and lodging.

And in mid-July, Restore Our Future wrote two checks to Sandie Tillotson, a cosmetics executive and a friend of Mr. Romney, reimbursing her for “event costs,” which appear to be associated with a fund-raiser held in her apartment on the top floor of the north tower of the Time Warner Center in Manhattan. Several weeks later, the Romney campaign also sent a check to the residential board of Ms. Tillotson’s building, which is home as well to the Mandarin Oriental hotel, for “facility rental/catering services.” (The campaign had a fund-raiser at the hotel on July 19.)

The overlapping connections of American Crossroads, the independent group tied to Karl Rove, with the Alexandria office suite are likely to draw more scrutiny in the general election, should Mr. Romney win the nomination. Mr. Forti is the group’s political director, and Crossroads is expected to be a big player in November.

While American Crossroads has not officially endorsed a candidate, it has been seen by some as tacitly supporting Mr. Romney. It issued a memorandum last month defending his electability in the face of attacks by the Obama campaign. That was soon followed by another, saying its earlier note “probably should have been clearer” that the group remained neutral in the Republican primaries.

A version of this article appears in print on February 26, 2012, on Page A1 of the New York edition with the headline: Fine Line Between ‘Super PACs’ and Campaigns. Order Reprints|Today's Paper|Subscribe